# Copyright 2021 Pex project contributors.
# Licensed under the Apache License, Version 2.0 (see LICENSE).

from __future__ import absolute_import

from pex.fetcher import URLFetcher
from pex.network_configuration import NetworkConfiguration
from pex.requirements import (
    Constraint,
    LocalProjectRequirement,
    PyPIRequirement,
    URLRequirement,
    VCSRequirement,
    parse_requirement_file,
    parse_requirement_strings,
)
from pex.typing import TYPE_CHECKING

if TYPE_CHECKING:
    from typing import Iterable, List, Optional, Tuple

    import attr  # vendor:skip

    from pex.requirements import ParsedRequirement
else:
    from pex.third_party import attr


def _as_str_tuple(items):
    # type: (Optional[Iterable[str]]) -> Tuple[str, ...]
    if not items:
        return ()
    return items if isinstance(items, tuple) else tuple(items)


@attr.s(frozen=True)
class RequirementConfiguration(object):
    requirements = attr.ib(default=(), converter=_as_str_tuple)  # type: Tuple[str, ...]
    requirement_files = attr.ib(default=(), converter=_as_str_tuple)  # type: Tuple[str, ...]
    constraint_files = attr.ib(default=(), converter=_as_str_tuple)  # type: Tuple[str, ...]

    def parse_requirements(self, network_configuration=None):
        # type: (Optional[NetworkConfiguration]) -> Tuple[ParsedRequirement, ...]
        parsed_requirements = []  # type: List[ParsedRequirement]
        if self.requirements:
            parsed_requirements.extend(parse_requirement_strings(self.requirements))
        if self.requirement_files:
            fetcher = URLFetcher(network_configuration=network_configuration)
            for requirement_file in self.requirement_files:
                parsed_requirements.extend(
                    requirement_or_constraint
                    for requirement_or_constraint in parse_requirement_file(
                        requirement_file, is_constraints=False, fetcher=fetcher
                    )
                    if isinstance(
                        requirement_or_constraint,
                        (PyPIRequirement, URLRequirement, VCSRequirement, LocalProjectRequirement),
                    )
                )
        return tuple(parsed_requirements)

    def parse_constraints(self, network_configuration=None):
        # type: (Optional[NetworkConfiguration]) -> Tuple[Constraint, ...]
        parsed_constraints = []  # type: List[Constraint]
        if self.constraint_files:
            fetcher = URLFetcher(network_configuration=network_configuration)
            for constraint_file in self.constraint_files:
                parsed_constraints.extend(
                    requirement_or_constraint
                    for requirement_or_constraint in parse_requirement_file(
                        constraint_file, is_constraints=True, fetcher=fetcher
                    )
                    if isinstance(requirement_or_constraint, Constraint)
                )
        return tuple(parsed_constraints)

    @property
    def has_requirements(self):
        # type: () -> bool
        return bool(self.requirements) or bool(self.requirement_files)
